Ann is a very kind and compassionate girl, enough for it to be noted by both Morgana and Sojiro Sakura. Years of isolation due to her looks have left her very withdrawn, with the belief that she's lost her place in the world, but this hasn't stopped her from opening up to the people close to her and have fun. She's able to press on without caring about the opinions of others due to her friendship with Shiho Suzui, who was her first real friend in Japan before joining the Phantom Thieves. She is shown to be a good judge of character, as she was the first person able to look past the rumors of the protagonist and see him for who he really is. Her good judgement of others is also shown by her willingness to forgive Makoto after learning her side of the story in the incident with Suguru Kamoshida, namely that she wanted to do something but felt powerless to stop him, having realized it wasn't too different from her own situation. Before this, she also comforts Makoto when she calls herself "scum of the Earth" due to her failure to help Kamoshida's victims, saying that if she really was scum, she wouldn't call herself such.
Although Ann is outwardly good and kind-hearted, and she genuinely wishes to help people in need, it comes at the cost of opening up her heart to inherent wrongness, evil and unforgiveness all at the ultimate result of making things better for others. She doesn't lose sight of this worldview for the sake of petty vengeance, especially when against Suguru Kamoshida, a terrible man that would try to hide in shallow honor and goodwill, even trying to offer his life to save himself. She does forgive the other students who ended up falling for rumors towards her, but she is especially hard on her closest friends when they instead engage in cowardly or self-destructive behavior, which includes Shiho and Alice Hiiragi. The common theme is that these people allowed their lives to be controlled by an outside source, such as Kamoshida or Hiiragi's bullies, as neither realized that they don't need their permission to live their lives. Again, she does so with sympathy towards their situations and the end result of helping them. In Ann's case, she disliked being someone who could only look on while other people suffered instead of stepping in: she explicitly did not want to return to the coward she used to be.
As a Phantom Thief, Ann becomes far more lively and energetic, with a strong will to never be abused or let abuses run unchecked. She agrees with Ryuji's desire to help those in need because she believes that if she doesn't, she'll go back to being the same as she was before. Although she understands that Kamoshida is ultimately the one at fault for what happened to Shiho, she can't help but feel partially responsible as well, due to frequently pushing Shiho to keep with the volleyball team despite the effect it was having on her. She also believes that she should have dared Kamoshida to take Shiho off the team when he threatened, as he wouldn't have done anything that would risk costing him games, but ultimately feels that she didn't believe in Shiho's ability. She reacts better to being told that she may be right rather than she can't blame herself, implying that she prefers people to be honest rather than sympathetic. Her Confidant deals largely with Ann's attempt to become a stronger person and come to terms with her guilt.
Ann's personable nature allows her to get along extremely well with her friends in the Phantom Thieves, and acts as a mediator to needless infighting between members of the group, especially between Ryuji and Morgana, ensuring they get along and remember they have a common goal. She is particularly considerate and kind towards Morgana in early encounters once she gets somewhat used to him, and may stand up to him at times if he gets provoked into a fight. She can still use a casual and sarcastic tone, such as with Ryuji, as on occasions they frequently bicker and exchange jabs with each other.
Ann can also be rather scornful when annoyed or upset, particularly during her early encounters with Makoto, and isn't even above using profanity when pushed over the edge. Ann can be cruel as well, as although she spares Kamoshida's life so he can confess his crimes and atone, she explains later that she did it not out of kindness, but so he would end up suffering and beg for forgiveness for the rest of his life, which she considers to be a fate worse than death, much to Ryuji's shock.
Ann's hobbies include shopping and playing video games, and she in particular considers the former to be "a great stress reliever." When Futaba points out that anything can be bought online, Ann is shocked by her approach, and says that "seeing and feeling it are the most important parts." She also has a massive sweet tooth for food such as cake, and has a weakness for crepe special menus like "extra extra cream." It gets to the point that she will sometimes eat nothing but dessert and neglect normal meals. However, she dislikes carbonated drinks and seems to prefer soy milk over cow milk. As revealed in a Mementos conversation, Ann has friends from overseas, who she seems to regularly keep in contact with.
While not as bad as Ryuji, Ann tends to struggle academically, performing poorly in every subject except English, which she mainly aces due to being bilingual. She can also be rather air-headed, particularly when it comes to her attempts to "strengthen her heart." Nevertheless, Ann is very smart in her own right. She is a good judge of character and has a keen eye for detail, such as when she senses anger and frustration coming from a painting at Ichiryusai Madarame's exhibit, and finds it hard to believe such a "cheerful and gentlemanly" man could have painted such a piece. Ultimately, she figures out that it was actually painted by Yusuke Kitagawa, who gave it to Madarame to pass off as his own. On a side-note, her acting skills are noted to be terrible, yet somehow fool people often. In Mementos, she reveals that her poor grades are actually the result of a lack of willingness to study, saying that whenever she tries, she ends up playing games instead.
In the beginning of the game, Ann has a modeling side-job as a hobby, although she doesn't want to make a living out of it just yet, as she is unsure how serious she wants to take it. Despite this and being generally confident about her body and physical appearance, Ann becomes flustered and embarrassed when she is forced into a situation that exposes her skin without her prior consent or desire. She has a tendency to mock or prank people who are ogling (such as Ryuji) and is disgusted with the idea of being used as a nude model for Yusuke's art. Ann can't stand it when people superficially value her for her body and nothing else, as if she is a thin-shelled, hollow doll with nothing on the inside or no other redeeming qualities.
She is also embarrassed by her Phantom Thief outfit at first, believing the tail is the only fine part of it, and commenting that she could never wear something like it out in public. Ann also vehemently rejects the Phantom's attempt to give her a "classy cat burglar" codename as they sound too "cute," instead deciding on the name "Panther," as it sounds "more ferocious." Her outfit is implied to be inspired by an anime Ann watched, in which she admired a "sexy" villain who was strong and confident, and took whatever she wanted whenever she wanted. In Mementos, she states that she likes using whips, and has gotten pretty good at handling one, before adding that she's not sure if that's something to be proud of. Ryuji even compares her to a dominatrix.
